Maya knows sirens are corrupt “mermaids-gone-wrong” and singing is forbidden because it’s dangerous. Still, when she hears siren song, she can barely suppress the rising urge to join in. When she witnesses a human diver attacking one of her kind—a mermaid—she can no longer quell the tide. The power of her voice drives back the attacker, bringing her into an unexpected alliance with a group of vigilante sirens who patrol the waters, protecting merfolk from human predators. Their enigmatic leader invites Maya to join them, promising to teach her how to harness the power of her voice—actions that could get her banished. With the sirens, Maya discovers inner strength and the power of community, even as the attacks and retaliations escalate. But when a group of surfers steal her adopted sister’s selkie skin, Maya pushes back too hard, and is forced to choose between staying silent and returning to the safety of her community, or risking banishment from her pod and staying true to herself.